Many diverse mechanical systems

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(No Transcript)
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Old Buildings

• Many diverse mechanical systems
• Older systems are sometimes more efficient

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Buildings We Examined
N
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Maxwell Dworkin

• New Building

• Hundreds of
• modifiable control points

• Managed by one central
• control system

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Heating

• From Western Ave.
• Through underground
• steam tunnel
• Carries steam, electrical,
• and communication lines

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Cooling

• From basement of Science Center

• Through buried insulated pipes

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Utilities
Water Supply and Return
Water pumps
Electrical Closet
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Other facilities
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Sources of Energy Consumption
Ventilation
Electricity
Hot and Chilled Water Usage
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Science Center
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William James Hall
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The Environment at Harvard
Encourage environmentally friendly policies
while maintaining pleasant atmosphere
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Buildings and the Environment
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Buildings and the Environment

• Energy Consumption as an Environmental Problem
• Particulate Matter in Air ? Respiratory Diseases
• Global Warming
• According to the Environmental Building News,
  April 2001 newsletter, commercial buildings
  represent
• 36 of all Energy Use in the United States
• 62 of electricity use
• 30 of Greenhouse Gas Emissions

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Impact Assessment

• For most of us 1,000,000,000 or 3.6 billion MWh
  and other such figures dont have any
  meaning.
• How can we measure impact?
• Dollars
• Energy Units
• CO2 emissions and equivalents
• Acres of Forest required for absorption
• 1.19 tons of CO2 to the acre US Commercial
  Forest

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Electricity at Harvard
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CO2 emissions for Electricity

• According to National Institute of Standards and
  Technology,
• 234.6 kg CO2 are generated for 1 MBTU Electricity
  
• 234.6 kg C02 / MMbtu
• 293.1 kWh / MMBtu
• 1350 kWh / acre US Commercial Forest

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CO2 emissions for Chilled Water

• Units of cooling
• 1 ton 12000 BTU / hr
• 1 ton-day means leaving a 12000 BTU / hr system
  on for 24 hours
• According to Bill Flanagan, manager at Chilled
  Water Plant
• 24 kWh ? 1 ton-day
• 56 ton-days / acre of US Forest

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CO2 emissions for Steam

• Steam comes from Commonwealth Electric Co. on
  Memorial Avenue
• Burn Grade 4 Bunker Oil
• Highly viscous
• In the winter, circulates throughout campus to be
  used in heating buildings
• Using an analysis of its density and heat of
  combustion,
• 12.5 MMBTU / acre US commercial Forest

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Conclusions

• Different forms of energy have different impacts
  upon the environment
• Conserving Energy, regardless of type, pays a
  double dividend
• Economic
• Environmental

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Maxwell Dworkin Utility Budget and Energy Balance

• Examining the Environmental Impact of
• Maxwell Dworkin

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Building Budgets

• Maxwell Dworkin
• FY2001 317 000
• 1380 acres of U.S. Commercial Forests
• 63 Harvard Yards

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Utility Cost per Square Foot
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MD Monthly Trends

• Cost of Electricity (in thousands of dollars)

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MD Monthly Trends

• Cost of Steam (in thousands of dollars)

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MD Monthly Trends

• Cost of Chilled Water (in thousands of dollars)

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MD Monthly Trends

• Cost of Electricity, Steam, and Chilled Water (in
  thousands of dollars)

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Energy Balance Model

• December

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Energy Balance Model

• July

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HVAC and Its Control

• An Overview of the Utility Control System,
• Air Handling Units, and Fan Coil Units

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Building System Controls
Maxwell Dworkins solution is Siemens Apogee
Technology
Diagram from OPC Foundation (OLE for Process
Control)
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Apogee Automation System

• What is Apogee?
• Pre-programmed control
• system that can operate
• the building equipment on
• site and remotely through
• web browsers.
• Important comfort and energy-saving strategy for
  MD
• Monitors daily scheduling of lighting, heating,
  cooling, and ventilation.

Photo taken of HAL 9000 from 2001 Space Oddessey
(1968 MGM Studios)
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Air Handling Unit
Photo taken of Air Handling Unit in the Science
Center
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Basic AHU Design
Building Ventilation Air handling units take in
fresh air from outside and deliver it to
appropriate space.
Diagram adapted from BLT at Colorado University
(Building as a Learning Tool).
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Basic AHU Design with Conditioning
Cooling Mode Above temperature set point
Cooling coil operates Heating Mode Below
temperature set point Heating coil operates
Diagram adapted from BLT at Colorado University
(Building as a Learning Tool).
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Complex AHU Design
Cooling Mode Above temperature set point
Cooling coil operates Heating Mode Below
temperature set point Heating coil operates
Diagram adapted from BLT at Colorado University
(Building as a Learning Tool).
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Fan Coil Unit
Setting
Space
Space
Coil
Cooling Mode Above temperature set point
Cooling coil operates Heating Mode Below
temperature set point Heating coil operates
Coil
Diagram adapted from Energy Savings at Iowa
State
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Energy Balance - Revisited
Heat Transfer to/from Outside
Sunload

• Ventilation,
• Recirculation,
• Conditioning
• AHUs
• Fan Coil
• Units

Electrical
Chilled Water
Steam
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An Adaptable Temperature Model
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Motivation

• Can we predict how a rooms temperature will
  change over the course of a day?
• How will any of our energy saving recommendations
  affect the office environment?
• Model is easily adaptable to any room with a
  thermostat if proper constants are changed

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Inputs and Outputs
Maxwell Dworkin 336
Sunload
Electric use
Conditioned air (gain or loss)
Fan Coil Unit (gain or loss)
Passive Heat Transfer (gain or loss)
People
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Building the Model
Tr(t) room temp. Cr room heat capacity ?(t)
scaling factor reflecting heat loss Qsrc(t) rate
of heat gains to the system Qfcu(u) rate of heat
supplied/removed from fan coil unit u thermostat
control temperature

• A Differential Equation
• Equation predicts room temperature Tr(t) as a
  function of the rates of heat gain and heat loss
  and the heat capacity of the room

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Building the Model
Tr(t) room temp. Cr room heat capacity ?(t)
scaling factor reflecting heat loss Qsrc(t) rate
of heat gains to the system Qfcu(u) rate of heat
supplied/removed from fan coil unit u thermostat
control temperature

• Cr Room heat capacity
• Sums the capacities to store heat of all exposed
  surfaces in the room--including objects (books,
  desks, chairs), walls, ceiling, and the floor
• where ?s is the mass density
• As is the area
• ds is the heat penetration depth
• Cp,s is the specific heat
• for each exposed surface s

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Building the Model
Tr(t) room temp. Cr room heat capacity ?(t)
scaling factor reflecting heat loss Qsrc(t) rate
of heat gains to the system Qfcu(u) rate of heat
supplied/removed from fan coil unit u thermostat
control temperature

• ?(t) Heat Loss Ratio
• Reflects current room temperature and heat
  leaving the system through passive transfer and
  air circulating out
• where k is a coefficient of passive heat
  transfer dependent on the windows and exterior
  walls
• Cair(t) is the heat capacity of the air leaving
  the room.

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Building the Model
Tr(t) room temp. Cr room heat capacity ?(t)
scaling factor reflecting heat loss Qsrc(t) rate
of heat gains to the system Qfcu(u) rate of heat
supplied/removed from fan coil unit u thermostat
control temperature

• Qsrc Rate of Heat Gains
• Sums the rates of heat gain from sunload,
  electrical devices, people, passive transfer, and
  conditioned air blowing in
• where Q1(t) is the summed heat gains from
  sunload, electrical use, and people
• Text(t) is the external temperature
• Tahu(t) is the temperature of the conditioned
  air entering the system

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Building the Model
Tr(t) room temp. Cr room heat capacity ?(t)
scaling factor reflecting heat loss Qsrc(t) rate
of heat gains to the system Qfcu(u) rate of heat
supplied/removed from fan coil unit u thermostat
control temperature

• Qfcu Heat input/output from fan coil
  units
• Fan coil unit supplies heat with hot water or
  removes heat with chilled water to control the
  room temperature

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Testing the Model Procedure

• Five day trial of the model
• Compared predictions to actual temperature data
  measured in Maxwell Dworkin 338
• (April 5, 2002 to April 10, 2002)
• We measured and recorded
• Occupancy levels
• Light levels
• Fan coil unit activity
• Room temperature next to the thermostat

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Testing the Model Results
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Applying the Model

• A simulated office
• Office heated mostly by sun and electricity
  (lights)
• Even without sun, building is being heated
  electrically
• Assumes thermal equilibrium
• i.e. constant temperature
• Sunny room on an April morning
• South-facing
• Single person

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Narrow Band Constraint

• Simulated graduate student office on June 1
• 4 people 9am - 8pm
• 1 person 8pm - 11pm
• Room temperature regulated by FCUs
• One exterior wall
• Two windows
• No sunload
• Active cooling needed

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Perils of Narrow Band Constraint

• Cooling more expensive than heating
• Heat is retained by building insulation
• Maintaining constant temperature is expensive
• May need both heating and cooling in same day
• Perhaps range can be broadened
• Broader range ? less conditioning
• But what defines a comfortable range?

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ASHRAE and Comfort

• ASHRAE
• American Society of Heating, Refrigeration, and
  Air-conditioning Engineers
• Psychrometric Chart
• Comfort zones based on temperature, relative
  humidity

Chart from 2001 ASHRAE Handbook
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Optimal Control

• Same room parameters as before
• Thermostat setting floats within comfort zone
• Much less cooling required
• Cut cooling cost by 18 in this case
• Many other simulations possible

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Conclusions

• Cooling needed most of the year
• Electrical and human heat counteract passive loss
• In offices, sunload also contributes to heat
  input
• Constant temperature is expensive
• We can widen the control range and still be
  comfortable
• But may still need heating and cooling in same
  day
• Applying floating control strategy over an entire
  year could reduce cooling cost up to 34

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Cooling and Chilled Water in Maxwell Dworkin
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An Outline of the Problem

• Inefficiencies in daily, weekly, and seasonal
  scheduling and in operation of overall control
  system
• Surprising trends in chilled water use
• Substantial use during the winter
• Opportunities to take advantage of other cooling
  mechanisms

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Chilled Water Basics

• How is chilled water produced?
• Chillers in basement of Science Center
• Provide water to buildings at 45ºF
• What is the unit of measurement for chilled
  water?
• TON-DAY
• Approximately 288,000 BTUs
• How is chilled water metered?
• Flow rate and temperature difference measured at
  chilled water plant
• Used to calculate ton-days for billing in 2-hour
  intervals

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The Chilled Water Cycle
CW Supply 45oF
Pump
Cooling Load
Valves
CW Return 60oF
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Chilled Water Usage

• Inside building, chilled water is used to
  provide
• Comfort Cooling
• Via fan coil units
• Offices, Research Labs, Common Spaces
• Cooling load varies throughout the day and year
• Scheduled 7 am 7 pm, 7 days a week
• Computer Load Cooling
• Computer Server Room, Telephone Equipment Room,
  EECS Mechanical Rooms
• Estimated cooling load 20 kW
• 24 hours a day, 7 days a week

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Hourly Chilled Water Trends
45 kW
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Inefficiencies in Control Operation

• Exceptions to 12-hour cooling scheme can be
  programmed
• Occupants may request extra cooling (i.e. 24
  hours)
• Changes sometimes forgotten
• Can result in rooms being cooled when unoccupied
• Not known unless Apogee is scrutinized
• Example Until last week, 13 rooms in Maxwell
  Dworkin were cooled 24 hours a day
• Occurring for an unknown period of time
• Difficult to estimate amount of wasted cooling
• Still nearly 50 of night-time chilled water
  usage unaccounted for

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Improving Control

• Apogee has capability for one-time exceptions
• Formalize process for changing cooling scheme
• Keep log or other records of what changes are
  made
• Periodically check system for unusual behavior
• Summary Awareness of operation of control system
  can prevent energy waste

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Daily Chilled Water Trends
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Cooling on the Weekend

• Offices, research labs, classrooms, and common
  spaces cooled 7 days a week
• Many of these spaces not occupied on weekends and
  heating load reduced
• Expanded allowable temperature range for
  unoccupied spaces
• Suggestion Schedule cooling Monday through
  Friday do not control weekend temperature

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Solutions for Weekend Cooling

• Use office simulation to predict effects of not
  cooling an unoccupied space
• Results Temperature will not exceed 95ºF, even
  during summer months
• Acceptable if space is unoccupied
• Occupants able to provide 3 hours of cooling via
  override requires no more than about 15 minutes
  to cool office to set temperature
• Suggestion Eliminate weekend cooling and only
  cool office to setpoint on Monday morning
• Effect Reduce weekend chilled water use to
  standard night-time levels

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Possible Savings

• Reduction of 10 to 25 in weekly chilled water
  use possible
• On a yearly basis
• Save up to 1600 ton-days
• Save 14,000
• About 28 acres of forest required to compensate
• Temperature effects can be reduced by air purges

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Monthly Chilled Water Trends
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Environmental cooling

• Design Issues
• Building is largely unoccupied in the early
  morning (3 a.m.)
• Start building at lower temperature in the
  morning
• Allow gradual temperature rise over the day
• Cooling not necessary until later in the day
• Take advantage of other forms of cooling

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Summer Night-time Air Purges

• Suggestion Run air handlers at coolest time of
  night to lower starting building temperature
• If outside air temperature and humidity are
  favorable, its possible to cool the building by
  exchanging inside air for outside air
• Simple way to get free cooling from alternate
  source
• During summer months, average low temperature
  between 60ºF and 65ºF

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Summer Night-time Air Purges
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Summer Night-time Air Purges
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Possible Savings

• Purges will reduce cooling load 7 days a week
• Can reduce effects of eliminating weekend cooling
• Possible to reduce cooling by up to 25,000 BTUs
  per office per day during the week
• For just the 45 faculty and staff offices
• 4.5 ton-days per day during the summer
• 3,000 per year
• About 5 acres of forest required to compensate
• Additional savings possible in research labs,
  common spaces, and classrooms

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Enhancing the Chilled Water System

• Create a closed loop system to take advantage of
  cold outside air
• Cool Down Ethylene Glycol in order to cool down
  water with heat exchanger
• Similar System in Sherman Fairchild to take
  advantage of waste heat

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Proposed Ethylene Glycol System
EG from Outside
Cooling Load
CW Supply 45oF
Valves
CW Return 60oF
EG to Outside
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Economic Analysis

• In discussion with Shooshanian Engineering on the
  question of installation and operational costs
• Potential Benefits
• Free cooling when Wet Bulb Temperature is below
  chilled water set point
• Using the Boston weather set, this represents a
  potential savings of 60 days of cooling during
  the winter
• Disadvantages
• Toxic
• Corrosive

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Conclusion

• Suggestions
• Reduce weekend cooling
• Use air purges to reduce summer cooling
• Consider alternative forms of cooling
• Annual savings estimate
• Approximately 1900 ton-days
• 17,000
• 33 acres of US Commercial Forest
• Low initial costs for control suggestions

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Carbon Dioxide Levels Within A Building
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Carbon Dioxide

• When humans breathe Oxygen it is converted to
  Carbon Dioxide within the body and exhaled
• Breathing within a closed, unventilated, space
  can significantly increase the CO2 level
• CO2 levels expressed in terms of parts per
  million (ppm)

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Appropriate Ventilation Levels

• The level of CO2 within a building reflects the
  level of the ventilation rate
• Outside fresh air CO2 levels usually range from
  380 to 420 ppm
• CO2 levels of 2500-5000ppm can cause headaches,
  and tiredness.

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Various Ventilation Levels
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Various Ventilation Levels
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Various Ventilation Levels
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Various Ventilation Levels
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Appropriate Ventilation Levels continued

• Measurements throughout Maxwell Dworkin indicate
  that CO2 levels remain below 600 ppm with an
  average of 500ppm
• ASHRAE recommends 1000 ppm as an appropriate
  upper bound for CO2 levels
• Additional support required to conclude that
  Maxwell Dworkin is always over-ventilated

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Differential Equation

• dc(t)/dt 1 / V 104N - Q(c(t) - c0)
• where
• c(t) concentration of CO2 within the room (ppm)
• c0 concentration of CO2 in outside air (ppm)
• V volume of the room (ft3)
• Q air inflow/outflow rate (ft3 / min)
• N number of people in the room (no units)

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CO2 Equation

• c(t) c(0)e-gt (c0 104N/Q)(1 - e-gt)
• where
• c(t) concentration of CO2 within the room (ppm)
• c0 concentration of CO2 in outside air (ppm)
• Q air inflow/outflow rate (ft3 / min)
• N number of people in the room (no units)
• g time constant Q / V (inverse minutes)
• C(0) represents the initial CO2 level within
  the building. Assumed to be 400ppm.

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CO2 Model of Floors 1,2,3
CO2 Levels (ppm)
Time (minutes)
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Conclusions

• Maxwell Dworkin is over-ventilated
• The CO2 Equation can be combined with population
  estimates and an upper bound for the CO2 level
  (1000ppm) to determine the minimum ventilation
  levels.

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Ventilation and Air Handling Units
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Ventilation Requirements
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Method of investigation

• Calculated the ventilation requirement
• Number of people
• Types of spaces people occupied
• Requirements of other spaces (kitchens,
  bathrooms, etc.)

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Method of investigation

• Calculated the ventilation requirement
• Number of people
• Types of spaces people occupied
• Requirements of other spaces (kitchens,
  bathrooms, etc.)
• Compared to actual ventilation provided

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Method of investigation

• Calculated the ventilation requirement
• Number of people
• Types of spaces people occupied
• Requirements of other spaces (kitchens,
  bathrooms, etc.)
• Compared to actual ventilation provided
• Measured CO2 levels
• Range 380 - 600 ppm

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Air Handling Units in Maxwell Dworkin

• 5 Air Handling Units service Maxwell Dworkin
• 3 types of systems
• Supply and return air system (AHU 2)
• Supply air only systems (AHUs 4 5)
• Supply and return with mixed air systems (AHUs 1
  3)

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Air Handling Unit 2

• Supply and return air system
• Constant supply flow rate of 2,000 cfm
• Operates 7 days a week from 7am - 7pm

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Air Handling Unit 2

• Basement

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Air Handling Unit 2

• Basement Ventilation Required
• Mechanical spaces 283 cfm

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Air Handling Unit 2

• Basement Ventilation Required
• Mechanical spaces 283 cfm
• Teaching labs 900 cfm
• Offices 180 cfm
• Bathrooms 600 cfm
• 1,963 cfm

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Exhaust Fans in the Basement

• In the Basement
• Exhaust Fans service the Bathrooms and Electrical
  Closet
• 600 cfm by exhaust fans

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Exhaust Fans in Maxwell Dworkin

• Throughout Maxwell Dworkin
• Exhaust Fans provide for the exhaust of air from
• Electrical closets
• Photocopy rooms
• Bathrooms
• Janitors Closets
• Kitchenettes

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Exhaust Fans in Maxwell Dworkin
3rd Floor
2nd Floor
1st Floor
Ground
Basement
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Air Handling Units 4 and 5

• AHU 4 and 5
• Supply air only system

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Air Handling Units 4 and 5

• AHU 4 and 5
• Supply air only system
• Serve Floors 1,2 and 3 in Maxwell Dworkin.
• AHU 4 supplies a constant flow rate of 8,215 cfm
• AHU 5 supplies a constant flow rate of 5,610 cfm
• Operate 7 days a week from 7am 7pm

From 4
From both
From 5
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Exhaust Air of Air Handling Units 4 and 5

• In the beginning of this semester
• 13,825 cfm AHUs 4 and 5 supply
• 7,980 cfm exhausted by exhaust fans
• 5,845 cfm leak out through windows and joints
• From our calculations
• 2,772 cfm of exhaust are required of the exhaust
  fans for Floors 1, 2, and 3
• Potential reduction 5,208 cfm

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Method of investigation

• Calculated the ventilation requirement
• Number of people
• Types of spaces people occupied
• Requirements of other spaces (kitchens,
  bathrooms, etc.)
• Compared to actual ventilation provided
• Measured CO2 levels
• Range 380 - 600 ppm

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Air Handling Units 4 and 5

• Occupancy of Maxwell Dworkin on floors
• 1, 2 and 3 is, on average, approximately 120
  people1
• ASHRAE standards cite 20 cfm of fresh air per
  person (office space).
• BOCA2 standards cite 20 cfm (office space).
• Massachusetts ventilation standards are based on
  BOCA.

1120 people figures from faculty, staff
graduate students lists 2BOCA Building Official
Code Administrators International Mechanical Code
2000
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Air Handling Units 4 and 5

• In the beginning of the semester

A H U
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Air Handling Units 4 and 5

• In the beginning of the semester

E F s
A H U
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Air Handling Units 4 and 5

• In the beginning of the semester

E F s
A H U
At 20 cfm, this allows for 262 people
(per person)
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Air Handling Units 4 and 5

• AHU 4 and 5 must supply amount required by
• occupancy load plus exhaust fans on floors
  1,2 and 3.
• Assume of 180 person occupancy 50 safety
  margin.
• Occupancy load requires 3,6001 cfm.
• Exhaust fans require 2,772 cfm.
• Total required supply for AHU 4 and 5 6,372 cfm
• 54 reduction
• At normal 120 occupancy 30 cfm per person

13,600 based on 20cfm per person at 180
occupancy
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Air Handling Units 4 and 5

• What happens to the CO2 level?

CO2 (ppm)
Minutes after 7am
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Air Handling Units 4 and 5

• What happens to the CO2 level?

680ppm
CO2 (ppm)
7pm
Minutes after 7am
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Air Handling Units 4 and 5

• AHU 4 and 5 supply air temperature set to 68oF
• A reduction in supplied cfm corresponds to less
  available heating/cooling energy in the total
  supply air.
• Must be compensated for allows for direct
  analysis of savings.

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Air Handling Units 4 and 5

• Winter time (October -gt mid-April)
• Supply air temperature can be lowered to account
  for cfm reduction lower to 63oF.
• Results in less hot water usage by AHU 4 and 5
• Corresponds to 0.20 savings per cfm per year.

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Air Handling Units 4 and 5

• Summer time

116
Air Handling Units 4 and 5

• Summer time
• Out of the comfort zone

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Air Handling Units 4 and 5

• Summer time
• Building setpoint can be increased to 76oF thus
  moving within comfort levels.
• AHU 4 and 5 can supply air at 68oF maintains
  available total energy.
• No additional chilled water required per cfm.

118
Air Handling Units 4 and 5

• What about weekends?
• No longer expect 120 occupancy.
• Early mornings and late afternoons less likely to
  be busy.

119
Air Handling Units 4 and 5

• What about weekends?
• No longer expect 120 occupancy.
• Early mornings and late afternoons less likely to
  be busy.
• Solution cut down on ventilation on weekends
  (Sat and Sun)
• Possible schedule
• On at 7am for one hour
• On from 11am -gt 1pm
• On from 4pm -gt 5pm
• Total weekend time 8 hours (previously 24 hours)

120
AHUs 4 and 5 Savings

• One cfm costs 2.331 per year to condition
• and circulate.

1 2.33 - cost based on 7 days a week operation,
12 hours a day
121
AHUs 4 and 5 Savings

• One cfm costs 2.331 per year to condition
• and circulate.
• Total current cost of running AHU 4 and 5 is
• 32,200.00.

1 2.33 - cost based on 7 days a week operation,
12 hours a day
122
AHUs 4 and 5 Savings

• One cfm costs 2.331 per year to condition
• and circulate.
• Total current cost of running AHU 4 and 5 is
• 32,200.00.
• Reduction in cfm supply of AHU 4 and 5 gives a
  17,400.00 annual savings

1 2.33 - cost based on 7 days a week operation,
12 hours a day
123
AHUs 4 and 5 Savings

• One cfm costs 2.331 per year to condition
• and circulate.
• Total current cost of running AHU 4 and 5 is
• 32,200.00
• Reduction in cfm supply of AHU 4 and 5 gives a
  17,400.00 annual savings
• Taking into account winter time and weekend
  savings gives a
• 21,200.00 TOTAL annual savings (58 acres of
  US forest)

1 2.33 - cost based on 7 days a week operation,
12 hours a day
124
AHUs 4 and 5 Payback Period

• How should such reductions be accomplished?
• Decrease in the fan speed of AHU 4 and 5 as well
  as exhaust fans.

125
AHUs 4 and 5 Payback Period

• How should such reductions be accomplished?
• Decrease in the fan speed of AHU 4 and 5 as well
  as exhaust fans.
• Suggestion 1 variable frequency drives
• Variable fan speed would allow alterations to be
  made to the system perhaps appropriate for AHU
  4 and 5.
• Accomplished by retrofitting fan motors with
  variable frequency drives.
• Cost - 14,000 -gt 15,000 per retrofit

126
AHUs 4 and 5 Payback Period

• Suggestion 2 Pulley ratio change
• All fan motors driven by a pulley belt like the
  fan belt in cars.
• Changing the pulley ratio can alter the exhaust
  rate.
• Cost effective.
• No need for variable exhaust rates all serviced
  spaces conform to code.

Safe to say payback period for modifications is
under 3 years
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Further evidence

• We are currently conducting an experiment in MD.

128
Further evidence

• We are currently conducting an experiment in MD.
• Less ventilation than we are recommending
• No adverse effects in CO2.
• No complaints.
• Our suggestions are occupant conscious, as well
  as
• economically and environmentally beneficial

129
Air Handling Unit Control

• Operation and Efficiency Analysis
• for AHUs 1 and 3 in Maxwell Dworkin

130
Air Handling Unit 1

• Serves lecture hall G115 ONLY
• Constant volume flow rate -
• 3380 CFM

Carbon Dioxide
Return Air
Humidity
Mixed Air Damper
Heating
Outside Air
Supply Air
Cooling
131
Sequence of Operation
Is it in day mode (7am-7pm)?
Yes
No
COOL DOWN
WARM UP
UNOCCUPIED
OCCUPIED
132
Occupied Mode for AHU 1
AHU 1
Damper Control
CO2
Enthalpy
Temperature
133
Sequence of Operation
Is it in day mode (7am-7pm)?
Yes
No
COOL DOWN
WARM UP
UNOCCUPIED
OCCUPIED
Current System
No
Is it 7pm?
Yes
134
CO2 Levels

• CO2 limit was set at 750 ppm
• Reset to 1000 ppm

135
Sequence of Operation
Is it in day mode (7am-7pm)?
Yes
No
COOL DOWN
WARM UP
UNOCCUPIED
OCCUPIED
Current System
Improvement
No
Is it 7pm?
Yes
136
Class Scheduling

• Many hours during the day that
• classroom is not in use
• Take advantage of class
• scheduler
• Possible to schedule based on
• CO2 levels
• (may cause problems with temperature)

137
Cost of Running AHU1

• Estimated costs
• heating and cooling 3,600 per year
• electricity for fan 1,200 per year
• Total Estimated cost 4,800 per year
• Scheduling would reduce running time by roughly
  1/3 which 1/3 of total cost
• Estimated Savings 1,600 per year

138
Occupied Mode for AHU 3
AHU 3
Damper Control
Temperature
Enthalpy
139
Air Handling Unit 3

• Provides air to ground floor by variable air
  volume boxes
• Variable volume flow rate
• Max - 17,210 CFM
• No Carbon Dioxide sensor

140
Variable Air Volume Box
Supplied at 64(?) F
Ground Floor Room
141
Sources of Savings

• Increase deadband (offset) temperature range
• Reduce cfm (volume flow rate) from VAV boxes into
  rooms and hallways
• Lower operating pressure for VAV boxes

142
Costs of Running AHU3

• Estimate costs
• heating and cooling 8,700 per year
• electricity for fans 4,000 per year
• Total estimated costs 12,700 per year
• Costs and savings estimates difficult to predict
  since this is a variable volume/variable
  frequency drive system

143
Heat Exchanger
Currently set at a supply temperature that is too
high Save money by lowering supply temperature
144
Lighting In Maxwell Dworkin

• An Analysis of the Current Lighting Situation and
  Proposals to Improve Efficiency

145
Background

• How do you measure light?
• Lumen
• A measurement of how much actual light is emitted
  from a light source
• Lux
• One lumen per square meter

146
Lighting Levels

• Illuminating Engineering Society Recommendations
  
• 200- 500 Lux
• Typical Measured Lighting Levels
• Dorm Room 600 Lux
• Fogg Museum 50-200 Lux
• Measured Lighting Levels for Maxwell Dworkin
• Ground Floor Hall 300 Lux
• Hallways 300 Lux
• Office with all lights on 1800 Lux
• Measured Lighting Levels for Pierce Hall
• Hallways 80 Lux

147
Maxwell Dworkin is overlit.

• Example a South-facing offices desk
• All lights on and blinds open 1800 lux
• 2/3 of the lights on and the blinds open 1700
  lux
• All lights on and blinds half open 800 lux
• Lights are on when there is sufficient daylight.
• Lights are on when no one is in the area.

Common Area
South-facing Room
148
Bulb Types
Fluorescent Bulbs
Incandescent Bulbs
T8 bulbs
Compact Fluorescents
Halogen
149
Contrast Levels

• Human eye perceives relative light levels, not
  absolutes.
• With appropriate contrast levels, need only 50
  Lux
• Examples of using Contrast Levels
• Blackboards
• Maxwell Dworking G115 lecture hall tables

150
Contrast Demonstration
151
Contrast Demonstration
152
Contrast Demonstration
153
Maxwell Dworkin is overlit.

• Current contrast levels make it difficult to see.

Maxwell Dworkin 300 Lux
154
Solutions Ground Floor

• Change to efficient light bulbs
• Hallways and lecture halls have
  halogen/incandescent lightbulbs

Halogen bulbs
Incandescent bullb
155
Solutions Ground Floor

• Change to efficient light bulbs
• Hallways and lecture halls have
  halogen/incandescent lightbulbs
• Should be changed to dimmable compact fluorescent
  lights
• Total Savings
• 4100
• 28 acres of
• required forest to
• compensate for
• CO2 emissions

156
Solutions - Offices

• Original lighting in faculty and staff offices
• 12 fluorescent bulbs, arranged in groups of 3
• All lights on, blinds half open 800 lux
• All lights on, all blinds closed 550 lux

Switch 1
Switch 2
157
Solutions - Offices

• Modified lighting in faculty and staff offices
• Lowered overhead lighting by a factor of two
• All lights on, blinds half open 640 lux
• All lights on, all blinds closed 280 lux

Switch 1
Switch 2
158
Solutions - Offices

• Modified lighting in faculty and staff offices
• Lowered overhead lighting by a factor of two
• All lights on, blinds half open 640 lux
• All lights on, all blinds closed 280 lux
• Compensated by adding task lamps, contrasting
  surface

(Picture of Barbara Groszs Desk)
159
Solutions - Offices

• Testimony
• I am completely satisfied with the new system.
  I believe the lighting meets my needs adequately.
  I am enjoying the thought that I am saving some
  energy
• -Dr. Joy Sircar
• My contrast pad and low lighting is working
  fine.
• -Peter Arvidson
• The desk lamp is excellent.
• -Prof. Barbara Grosz

160
Solutions - Offices

• Cost of installation
• Task lamps
• 45 offices x 52 2340
• Contrast pads
• 45 offices x 3 135
• Savings
• Reduced wattage by ½
• Affects electrical and chilled water consumption
• Assumed average 8-hour work day
• Savings 3300 per year
• 23 Acres of forest needed to compensate for CO2
  emissions

161
Solutions Common Areas/Hallways

• Addition of motion/light detectors in hallways
  and common areas

• No lights on when there are no people
• No lights on when there is sufficient lighting

162
Solutions Common Areas/Hallways

• (picture of where to put motion detectors in MD
  basement)

163
Solutions Common Areas/Hallways

• Costs
• Cost of detectors 2400
• Cost of installation
• Cheap for offices
• More complex for hallways
• Savings
• 5500 per year
• 37 Acres of forest needed to compensate for CO2
  emissions

164
Solutions Common Areas/Hallways

• Lower lighting levels in hallways combined with
  repainting
• Hallways look dark because of the darkness of the
  colors of the surrounding walls

Pierce Hall 80 Lux
Maxwell Dworkin 300 Lux
165
Total Savings
166
Efficiency Recommendations For University
Buildings
167
William James Hall and Science Center
168
Science Center And William James Hall

• Both are large buildings with key similarities
• classrooms
• offices
• lobbies / common areas
• Large AHUs with no fan coils

169
Ventilation

• CO2 levels within the buildings suggest that both
  The Science Center and William James Hall are
  over-ventilated (well below 1000 ppm).
• CO2 levels within Science Center range from
  450-575ppm.
• CO2 levels within William James Hall range from
  475-650ppm.
• Similarity to Maxwell Dworkin suggests
  possibility for energy savings.

170
Lighting Levels

• Average lighting levels in The Science Center and
  William James above 500 lux
• Overlit areas are indicative of possible energy
  savings
• Several of the solutions recommended for Maxwell
  Dworkin possibly applicable

171
Recommendation

• Apply recommendations for Maxwell Dworkin to
  Other buildings.
• Reduce ventilation levels
• Conduct night-time fresh-air purges
• Reduce lighting levels, install light level
  sensors, motion detectors utilize color contrasts

172
Efficient Air Conditioning

• A Psychrometric Analysis System To Improve Air
  Conditioning Efficiency In Large Buildings by
  Brian W. Schoenbeck S.B.02
• Windows-based software package
• Air exchange based on the psychrometric
  properties
• Program instructs the buildings ventilation
  system
• Includes night-time purges when economically
  advantageous
• Preferable over current summer/winter air
  conditioning schedules

173
Total Savings EstimateFor Maxwell Dworkin
174
Estimated Savings
175
Estimated Savings
176
Estimated Savings
Monetary Savings 31,000 per year
Environmental Savings 63 acres per year
177
Estimated Savings
Monetary Savings 55,000 per year
Environmental Savings 128 acres per year
178
Estimated Savings
Monetary Savings 68,000 per year
Environmental Savings 216 acres per year
179
Cost-Benefit Analysis

• Electricity and Lighting
• 4,700 to install motion detectors and buy lamps
• Ventilation
• Alternating Schedule 4,000
• Changing Pulley Ratio 6,000
• Installing VFD on AHU 4 and 5 34,000
• One time minimum cost of 8,700 would pay for
  itself in 2 months
• Even the more expensive 38,700 solution would
  pay for itself in 8 months

180
Acknowledgements

• Prof. Michelle Addington
• Peter Arvidson
• Prof. Michael Brandstein
• Prof. Roger Brockett
• Susyrati Bunanta
• Frank DeCosta
• Jeff Deyette
• Armond Diaz
• Scott Gaines
• Prof. Barbara Grosz
• Jean Humber
• Ed Jackson
• Jonathan Kanda
• Greg Kousidis

• Xuan Liang
• Prof. David Parkes
• Jay Phillips
• David Richards
• Stephen Robichaud
• Dr. Joy Sircar
• Joe Ustinowich
• Prof. Gu-Yeon Wei
• Prof. Woodward Yang
• Rich Zitola
• Coaching Staff
• Prof. Fred Abernathy
• Prof. Al Pandiscio
• Aaron Dollar